The present invention relates to a rotary recliner for mounting an adjustable seat back to a body supporting seat cushion and in particular, to improvements in such a recliner which reduce the lateral movement between an outer and inner gear.
Rotary recliners for adjustable vehicle seats which employ a pair of mating gears, an inner gear and an outer gear rotating about a common pivot, are well known. Such recliners have a first component attached to the body supporting seat cushion and a second component attached to the seat back. The two recliner components are coupled together for rotation relative to one another about a pivot shaft. One recliner component carries an inner spur gear, having outwardly extending teeth, while the other component carries an outer gear having inwardly directed teeth. The inner gear has at least one less tooth than the outer gear and has a diameter which is smaller than the diameter of the outer gear by at least the radial height of the outer gear teeth.
The inner gear is mounted on an eccentric so as to bias the inner gear in one direction radially relative to the outer gear. This results in meshing of gear teeth on one side and a clearance between the gear teeth on the opposite side. Rotation of the eccentric causes the area of teeth mesh to move circumferentially around the outer gear whereby the difference in the number of gear teeth produces rotation of the inner gear relative to the outer gear.
After adjustment of the seat back, the seat back is held in its adjusted position by the eccentric maintaining the meshing of the inner gear and outer teeth. The recliner is self locking in the sense that forces applied to the seat back can not cause a rotation of the eccentric and movement of the seat back. Only rotation of the eccentric by the operating handle produces a change in the seat back position. A certain amount of free play, i.e. clearance between the gear teeth is necessary for proper operation of the recliner. However, such free play can cause lateral movement of the inner gear—in other words, movement laterally along the axis of rotation. Such lateral movement can reduce the overall strength of the recliner and cause low overall product life.
Various approaches have been taken to reduce or compensate for such lateral movement. One approach is to increase the thickness of the teeth in the inner gear. However, this approach only compensates for such lateral movement and in doing so causes more cost and product packaging size to be used.
Another approach can be seen in FIGS. 3 and 4. Both Figures show a recliner mechanism having two separate covers added which only partially (less than 360 degrees) enclose the gears. FIG. 3 shows a partial cover 20 which is mounted to a portion of the seat back frame; however, the cover 20 only retains the inner gear for approximately 170 degrees. Similarly, the cover 30 in FIG. 4 only retains approximately 120 degrees of the outer gear.
It is an object of the present invention to provide an improved recliner which is easy to construct, eliminates lateral movement between the gears and which has high strength to resist loads during a vehicle collision.
The recliner of the present invention utilizes an inner retainer mounted to an outer gear for retaining an inner gear from lateral movement. The retainer is a one-piece construction, circular-shaped, and provides 360 degrees of support to the inner gear. Since the retainer provides 360 degrees of support to the inner gear, the construction of the gears can be less expensive reducing the overall cost of the recliner while improving performance. For example, the gears could be stamped sheet metal with teeth formed from less material thickness.
Further objects, features, and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.